Ziegler-natta catalyst for polyolefins

ABSTRACT

A Ziegler-Natta type catalyst component can be produced by a process comprising contacting a magnesium dialkoxide compound with a halogenating agent to form a reaction product A, and contacting reaction product A with a first, second and third halogenating/titanating agents. Catalyst components, catalysts, catalyst systems, polyolefin, products made therewith, and methods of forming each are disclosed. The reaction products can be washed with a hydrocarbon solvent to reduce titanium species [Ti] content to less than about 100 mmol/L.

REFERENCE TO RELATED APPLICATION

The present application is a Continuation-in-part of U.S. patentapplication Ser. No. 09/687,560, entitled, Ziegler-Natta Catalyst ForNarrow to Broad MWD of Polyolefins, Method of Making, Method of Using,And Polyolefins Made Therewith, filed Oct. 13, 2000, U.S. Pat. No.6,693,058 incorporated herein by reference, which is aContinuation-in-part of U.S. patent application Ser. No. 08/789,862,entitled, Ziegler-Natta Catalysts for Olefin Polymerization, filed Jan.28, 1997, which issued as U.S. Pat. No. 6,174,971 on Jan. 16, 2001, alsoincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to catalysts, to methods ofmaking catalysts, to methods of using catalysts, to methods ofpolymerizing, and to polymers made with such catalysts. Moreparticularly, the present invention relates to polyolefin catalysts andto Ziegler-Natta catalysts, to methods of making such catalysts, tomethods of using such catalysts, to polyolefin polymerization, and topolyolefins.

2. Description of the Related Art

Olefins, also called alkenes, are unsaturated hydrocarbons whosemolecules contain one or more pairs of carbon atoms linked together by adouble bond. When subjected to a polymerization process, olefins can beconverted to polyolefins, such as polyethylene and polypropylene. Onecommonly used polymerization process involves contacting an olefinmonomer with a Ziegler-Natta type catalyst system. Many Ziegler-Nattatype polyolefin catalysts, their general methods of making, andsubsequent use, are well known in the polymerization art. Typically,these systems include a Ziegler-Natta type polymerization catalystcomponent; a co-catalyst; and an electron donor compound. AZiegler-Natta type polymerization catalyst component can be a complexderived from a halide of a transition metal, for example, titanium,chromium or vanadium, with a metal hydride and/or a metal alkyl that istypically an organoaluminum compound. The catalyst component is usuallycomprised of a titanium halide supported on a magnesium compoundcomplexed with an alkylaluminum. There are many issued patents relatingto catalysts and catalyst systems designed primarily for thepolymerization of propylene and ethylene that are known to those skilledin the art. Examples of such catalyst systems are provided in U.S. Pat.Nos. 4,107,413; 4,294,721; 4,439,540; 4,114,319; 4,220,554; 4,460,701;4,562,173; 5,066,738, and 6,174,971 which are incorporated by referenceherein.

Conventional Ziegler-Natta catalysts comprise a transition metalcompound generally represented by the formula: MR_(x) where M is atransition metal compound, R is a halogen or a hydrocarboxyl, and x isthe valence of the transition metal. Typically, M is selected from agroup IV to VII metal such as titanium, chromium, or vanadium, and R ischlorine, bromine, or an alkoxy group. Common transition metal compoundsare TiCl₄, TiBr₄, Ti(OC₂H₅)₃Cl, Ti(OC₃H₇)₂Cl₂, Ti(OC₆H₁₃)₂Cl₂,Ti(OC₂H₅)₂Br₂, and Ti(OC₁₂H₂₅)Cl₃. The transition metal compound istypically supported on an inert solid, e.g., magnesium chloride.

Ziegler-Natta catalysts generally are provided on a support, i.e.deposited on a solid crystalline support. The support can be an inertsolid, which is chemically unreactive with any of the components of theconventional Ziegler-Natta catalyst. The support is often a magnesiumcompound. Examples of the magnesium compounds which can be used toprovide a support source for the catalyst component are magnesiumhalides, dialkoxymagnesiums, alkoxymagnesium halides, magnesiumoxyhalides, dialkylmagnesiums, magnesium oxide, magnesium hydroxide, andcarboxylates of magnesium.

The properties of the polymerization catalyst can affect the propertiesof the polymer formed using the catalyst. For example, polymermorphology typically depends upon catalyst morphology. Good polymermorphology includes uniformity of particle size and shape and anacceptable bulk density. Furthermore, it is desirable to minimize thenumber of very small polymer particles (i.e., fines) for variousreasons, such as for example, to avoid plugging transfer or recyclelines. Very large particles also must be minimized to avoid formation oflumps and strings in the polymerization reactor.

Another polymer property affected by the type of catalyst used is themolecular weight distribution (MWD), which refers to the breadth ofvariation in the length of molecules in a given polymer resin. Inpolyethylene for example, narrowing the MWD may improve toughness, i.e.,puncture, tensile, and impact performance. On the other hand, a broadMWD can favor ease of processing and melt strength.

While much is known about Ziegler-type catalysts, there is a constantsearch for improvements in their polymer yield, catalyst life, catalystactivity, and in their ability to produce polyolefins having certainproperties.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a process for making acatalyst comprising: a) contacting a magnesium dialkoxide compound witha halogenating agent to form a reaction product A; b) contactingreaction product A with a first halogenating/titanating agent to formreaction product B; c) contacting reaction product B with a secondhalogenating/titanating agent to form reaction product C; and d)contacting reaction product C with a third halogenating/titanating agentto form reaction product D. The second and third halogenating/titanatingagents can comprise titanium tetrachloride. The second and thirdhalogenating/titanating steps can each comprise a titanium to magnesiumratio in the range of about 0.1 to 5. The reaction products A, B and Ccan each be washed with a hydrocarbon solvent prior to subsequenthalogenating/titanating steps. The reaction product D can be washed witha hydrocarbon solvent until titanium species [Ti] content is less thanabout 100 mmol/L.

Another embodiment of the present invention provides a polyolefincatalyst produced by a process generally comprising contacting acatalyst component of the invention together with an organometallicagent. The catalyst component is produced by a process as describedabove. The catalysts of the invention can have a fluff morphologyamenable to polymerization production processes, and may provide apolyethylene having a molecular weight distribution of at least 5.0 andmay provide uniform particle size distributions with low levels ofparticles of less than about 125 microns. The activity of the catalystis dependent upon the polymerization conditions. Generally the catalystwill have an activity of at least 5,000 gPE/g catalyst, but the activitycan also be greater than 50,000 gPE/g catalyst or greater than 100,000gPE/g catalyst.

Even another embodiment of the present invention provides a polyolefinpolymer produced by a process comprising: a) contacting one or moreolefin monomers together in the presence of a catalyst of the invention,under polymerization conditions; and b) extracting polyolefin polymer.Generally the monomers are ethylene monomers and the polymer ispolyethylene.

Yet another embodiment of the present invention provides a film, fiber,pipe, textile material or article of manufacture comprising polymerproduced by the present invention. The article of manufacture can be afilm comprising at least one layer comprising a polymer produced by aprocess comprising a catalyst of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the settling efficiency curves for polymer made usinga catalyst of the invention (Example 1), and polymer made using aconventional catalyst (Comparative Example 4).

DETAILED DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, a method for making acatalyst component generally includes the steps of forming a metaldialkoxide from a metal dialkyl and an alcohol, halogenating the metaldialkoxide to form a reaction product, contacting the reaction productwith one or more halogenating/titanating agent in three or more steps toform a catalyst component, and then treating the catalyst component witha preactivation agent such as an organoaluminum.

One embodiment of the present invention can be generally as follows:

1. MRR′+2R″OH→M(OR″)₂

2. M(OR″)₂+ClAR′″_(x)→“A”

3. “A”+TiCl₄/Ti (OR″″)₄→“B”

4. “B”+TiCl₄→“C”;

5. “C”+TiCl₄→“D”

6. “D”+preactivating agent→catalyst

In the above formulas, M can be any suitable metal, usually a Group IIAmetal, typically Mg. In the above formulas, R, R′, R″, R′″, and R″″ areeach independently hydrocarbyl or substituted hydrocarbyl moieties, withR and R′ having from 1 to 20 carbon atoms, generally from 1 to 10 carbonatoms, typically from 2 to 6 carbon atoms, and can have from 2 to 4carbon atoms. R″ generally comprises from 3 to 20 carbon atoms, R′″generally comprises from 2-6 carbon atoms, and R″″ generally comprisesfrom 2-6 carbon atoms and is typically butyl. Any combination of two ormore of R, R′, R″, R′″, and R″″ can be used, may be the same, or thecombination of the R groups may be different from one another.

In the above embodiment comprising formula ClAR′″_(x), A is anonreducing oxyphilic compound which is capable of exchanging onechloride for an alkoxide, R′″ is a hydrocarbyl or substitutedhydrocarbyl, and x is the valence of A minus 1. Examples of A includetitanium, silicon, aluminum, carbon, tin and germanium, typically istitanium or silicon wherein x is 3. Examples of R′″ include methyl,ethyl, propyl, isopropyl and the like having 2-6 carbon atoms.Nonlimiting examples of a chlorinating agent that can be used in thepresent invention are ClTi(O^(i)Pr)₃ and ClSi(Me)₃.

The metal dialkoxide of the above embodiment is chlorinated to form areaction product “A”. While the exact composition of product “A” isunknown, it is believed that it contains a partially chlorinated metalcompound, one example of which may be ClMg(OR″).

Reaction product “A” is then contacted with one or morehalogenating/titanating agent, such as for example a combination ofTiCl₄ and Ti(OBu)₄, to form reaction product “B”. Reaction product “B”which is probably a complex of chlorinated and partially chlorinatedmetal and titanium compounds. Reaction product “B” can comprise atitanium impregnated MgCl₂ support and for example, may possibly berepresented by a compound such as (MCl₂)_(y) (TiCl_(x)(OR)_(4-x))_(z).Reaction product “B” can be precipitated as a solid from the catalystslurry.

The second halogenation/titanation step produces reaction product, orcatalyst component, “C” which is also probably a complex of halogenatedand partially halogenated metal and titanium compounds but differentfrom “B” and may possibly be represented by (MCl₂)_(y)(TiCl_(x′)(OR)_(4-x′))_(z′). It is expected that the level ofhalogenation of “C” would be greater than that of product “B”. Thisgreater level of halogenation can produce a different complex ofcompounds.

The third halogenation/titanation step produces a reaction product, orcatalyst component, “D” which is also probably a complex of halogenatedand partially halogenated metal and titanium compounds but differentfrom “B” and “C”, and may possibly be represented by (MCl₂)_(y)(TiCl_(x″)(OR)_(4-x″))_(z″). It is expected that the level ofhalogenation of “D” would be greater than that of product “C”. Thisgreater level of halogenation would produce a different complex ofcompounds. While this description of the reaction products offers themost probable explanation of the chemistry at this time, the inventionas described in the claims is not limited by this theoretical mechanism.

Metal dialkyls and the resultant metal dialkoxides suitable for use inthe present invention can include any that can be utilized in thepresent invention to yield a suitable polyolefin catalyst. These metaldialkoxides and dialkyls can include Group IIA metal dialkoxides anddialkyls. The metal dialkoxide or dialkyl can be a magnesium dialkoxideor dialkyl. Non-limiting examples of suitable magnesium dialkyls includediethyl magnesium, dipropyl magnesium, dibutyl magnesium,butylethylmagnesium, etc. Butylethylmagnesium (BEM) is one suitablemagnesium dialkyl.

In the practice of the present invention, the metal dialkoxide can be amagnesium compound of the general formula Mg(OR″)₂ where R″ is ahydrocarbyl or substituted hydrocarbyl of 1 to 20 carbon atoms.

The metal dialkoxide can be soluble and is typically non-reducing. Anon-reducing compound has the advantage of forming MgCl₂ instead ofinsoluble species that can be formed by the reduction of compounds suchas MgRR′, which can result in the formation of catalysts having a broadparticle size distribution. In addition, Mg(OR″)₂, which is lessreactive than MgRR′, when used in a reaction involving chlorination witha mild chlorinating agent, followed by subsequenthalogenation/titanation steps, can result in a more uniform product,e.g., better catalyst particle size control and distribution.

Non-limiting examples of species of metal dialkoxides which can be usedinclude magnesium butoxide, magnesium pentoxide, magnesium hexoxide,magnesium di(2-ethylhexoxide), and any alkoxide suitable for making thesystem soluble.

As a non-limiting example, magnesium dialkoxide, such as magnesium di(2-ethylhexoxide), may be produced by reacting an alkyl magnesiumcompound (MgRR′) with an alcohol (ROH), as shown below.MgRR′+2R″OH→Mg(OR″)₂+RH+R′H

The reaction can take place at room temperature and the reactants form asolution. R and R′ may each be any alkyl group of 1-10 carbon atoms, andmay be the same or different. Suitable MgRR′ compounds include, forexample, diethyl magnesium, dipropyl magnesium, dibutyl magnesium andbutyl ethyl magnesium. The MgRR′ compound can be BEM, wherein RH and R′Hare butane and ethane, respectively.

In the practice of the present invention, any alcohol yielding thedesired metal dialkoxide may be utilized. Generally, the alcoholutilized may be any alcohol of the general formula R″OH where R″ is analkyl group of 2-20 carbon atoms, the carbon atoms can be at least 3, atleast 4, at least 5, or at least 6 carbon atoms. Non-limiting examplesof suitable alcohols include ethanol, propanol, isopropanol, butanol,isobutanol, 2-methyl-pentanol, 2-ethylhexanol, etc. While it is believedthat almost any alcohol may be utilized, linear or branched, a higherorder branched alcohol, for example, 2-ethyl-1-hexanol, can be utilized.

The amount of alcohol added can vary, such as within a non-exclusiverange of 0 to 10 equivalents, is generally in the range of about 0.5equivalents to about 6 equivalents (equivalents are relative to themagnesium or metal compound throughout), and can be in the range ofabout 1 to about 3 equivalents.

Alkyl metal compounds can result in a high molecular weight species thatis very viscous in solution. This high viscosity may be reduced byadding to the reaction an aluminum alkyl such as, for example,triethylaluminum (TEAl), which can disrupt the association between theindividual alkyl metal molecules. The typical ratio of alkyl aluminum tometal can range from 0.001:1 to 1:1, can be 0.01 to 0.5:1 and also canrange from 0.03:1 to 0.2:1. In addition, an electron donor such as anether, for example, diisoamyl ether (DIAE), may be used to furtherreduce the viscosity of the alkyl metal. The typical ratio of electrondonor to metal ranges from 0:1 to 10:1 and can range from 0.1:1 to 1:1.

Agents useful in the step of halogenating the metal alkoxide include anyhalogenating agent which when utilized in the present invention willyield a suitable polyolefin catalyst. The halogenating step can be achlorinating step where the halogenating agent contains a chloride (i.e,is a chlorinating agent).

Halogenating of the metal alkoxide compound is generally conducted in ahydrocarbon solvent under an inert atmosphere. Non-limiting examples ofsuitable solvents include toluene, heptane, hexane, octane and the like.In this halogenating step, the mole ratio of metal alkoxide tohalogenating agent is generally in the range of about 6:1 to about 1:3,can be in the range of about 3:1 to about 1:2, can be in the range ofabout 2:1 to about 1:2, and can also be about 1:1.

The halogenating step is generally carried out at a temperature in therange of about 0° C. to about 100° C. and for a reaction time in therange of about 0.5 to about 24 hours.

The halogenating step can be carried out at a temperature in the rangeof about 20° C. to about 90° C. and for a reaction time in the range ofabout 1 hour to about 4 hours.

Once the halogenating step is carried out and the metal alkoxide ishalogenated, the halide product “A” can be subjected to two or morehalogenating/titanating treatments.

The halogenation/titanation agents utilized can be blends of twotetra-substituted titanium compounds with all four substituents beingthe same and the substituents being a halide or an alkoxide or phenoxidewith 2 to 10 carbon atoms, such as TiCl₄ or Ti(OR″″)₄. Thehalogenation/titanation agent utilized can be a chlorination/titanationagent.

The halogenation/titanation agent may be a single compound or acombination of compounds. The method of the present invention providesan active catalyst after the first halogenation/titanation; however,there are desirably a total of at least three halogenation/titanationsteps.

The first halogenation/titanation agent is typically a mild titanationagent, which can be a blend of a titanium halide and an organictitanate. The first halogenation/titanation agent can be a blend ofTiCl₄ and Ti(OBu)₄ in a range from 0.5:1 to 6:1 TiCl₄/Ti(OBu)₄, theratio can be from 2:1 to 3:1. It is believed that the blend of titaniumhalide and organic titanate react to form a titanium alkoxyhalide,Ti(OR)_(a)X_(b), where OR and X are alkoxide and halide, respectivelyand a+b is the valence of titanium, which is typically 4.

In the alternative, the first halogenation/titanation agent may be asingle compound. Examples of a first halogenation/titanation agent areTi(OC₂H₅)₃Cl, Ti(OC₂H₅)₂Cl₂, Ti(OC₃H₇)₂Cl₂, Ti(OC₃H₇)₃Cl, Ti(OC₄H₉)Cl₃,Ti(OC₆H₁₃)₂Cl₂, Ti(OC₂H₅)₂Br₂, and Ti(OC₁₂H₅)Cl₃.

The first halogenation/titanation step is generally carried out by firstslurrying the halogenation product “A” in a hydrocarbon solvent at roomtemperature/ambient temperature. Nonlimiting examples of suitablehydrocarbons solvent include heptane, hexane, toluene, octane and thelike. The product “A” can be at least partially soluble in thehydrocarbon solvent.

A solid product “B” is precipitated at room temperature following theaddition of the halogenation/titanation agent to the soluble product“A”. The amount of halogenation/titanation agent utilized must besufficient to precipitate a solid product from the solution. In general,the amount of halogenation/titanation agent utilized, based on the ratioof titanium to metal, will generally be in the range of about 0.5 toabout 5, typically in the range of about 1 to about 4, and can be in therange about 1.5 to about 2.5.

The solid product “B” precipitated in this first halogenation/titanationstep is then recovered by any suitable recovery technique, and thenwashed at room/ambient temperature with a solvent, such as hexane.Generally, the solid product “B” is washed until the [Ti] is less thanabout 100 mmol/L. Within the present invention [Ti] represents anytitanium species capable of acting as a second generation Zieglercatalyst, which would comprise titanium species that are not part of thereaction products as described herein. The resulting product “B” is thensubjected to a second and third halogenating/titanating steps to produceproducts “C” and “D”. After each halogenating/titanating step the solidproduct can be washed until the [Ti] is less than a desired amount. Forexample, less than about 100 mmol/L, less than about 50 mmol/L, or lessthan about 10 mmol/L. After the final halogenating/titanating step, theproduct can be washed until the [Ti] is less than a desired amount, forexample, less than about 20 mmol/L, less than about 10 mmol/L, or lessthan about 1.0 mmol/L. It is believed that a lower [Ti] can produceimproved catalyst results by reducing the amount of titanium that canact as a second generation Ziegler species. It is believed that a that alower [Ti] can be a factor in producing improved catalyst results suchas a narrower MWD.

The second halogenation/titanation step is generally carried out byslurrying the solid product recovered from the first titanation step,solid product “B”, in a hydrocarbon solvent. Hydrocarbon solvents listedas suitable for the first halogenation/titanation step may be utilized.The second and third halogenation/titanation steps can utilize adifferent compound or combination of compounds from the firsthalogenation/titanation step. The second and thirdhalogenation/titanation steps can utilize the same agent at aconcentration that is stronger than that used in the firsthalogenation/titanation agent, but this is not a necessity. The secondand third halogenating/titanating agents can be a titanium halide, suchas titanium tetrachloride (TiCl₄). The halogenation/titanation agent isadded to the slurry. The addition can be carried out at ambient/roomtemperature, but can also be carried out at temperatures and pressuresother than ambient.

Generally, the second and third halogenation/titanation agents comprisetitanium tetrachloride. Typically the second and thirdhalogenation/titanation steps each comprise a titanium to magnesiumratio in a range of about 0.1 to 5, a ratio of about 2.0 can also beused, and a ratio of about 1.0 can be used. The thirdhalogenation/titanation step is generally carried out at roomtemperature and in a slurry, but can also be carried out at temperaturesand pressures other than ambient.

The amount of titanium tetrachloride utilized, or alternatehalogenation/titanation agent, may also be expressed in terms ofequivalents, an equivalent herein is amount of titanium relative to themagnesium or metal compound. The amount of titanium of each of thesecond and third halogenating/titanating steps will generally be in therange of about 0.1 to about 5.0 equivalents, can be in the range ofabout 0.25 to about 4 equivalents, typically is in the range of about0.3 to about 3 equivalents, and it can be desirable to be in the rangeof about 0.4 to about 2.0 equivalents. In one particular embodiment, theamount of titanium tetrachloride utilized in each of the second andthird halogenation/titanation steps is in the range of about 0.45 toabout 1.5 equivalent.

The catalyst component “D” made by the above described process may becombined with an organometallic catalyst component (a “preactivatingagent”) to form a preactivated catalyst system suitable for thepolymerization of olefins. Typically, the preactivating agents which areused together with the transition metal containing catalyst component“D” are organometallic compounds such as aluminum alkyls, aluminum alkylhydrides, lithium aluminum alkyls, zinc alkyls, magnesium alkyls and thelike.

The preactivating agent is generally an organoaluminum compound. Theorganoaluminum preactivating agent is typically an aluminum alkyl of theformula AlR₃ wherein at least one R is an alkyl having 1-8 carbon atomsor a halide, and wherein each of the R may be the same or different. Theorganoaluminum preactivating agent can be a trialkyl aluminum such as,for example, trimethyl aluminum (TMA), triethyl aluminum (TEAl) andtriisobutyl aluminum (TiBAl). The ratio of Al to titanium can be in therange from 0.1:1 to 2:1 and typically is 0.25:1 to 1.2:1.

Optionally, the Ziegler-Natta catalyst may be pre-polymerized.Generally, a prepolymerization process is affected by contacting a smallamount of monomer with the catalyst after the catalyst has beencontacted with the co-catalyst. A pre-polymerization process isdescribed in U.S. Pat. Nos. 5,106,804; 5,153,158; and 5,594,071, herebyincorporated by reference.

The catalyst of the present invention may be used in any process for thehomopolymerization or copolymerization of any type of α-olefins. Forexample, the present catalyst can be useful for catalyzing ethylene,propylene, butylene, pentene, hexene, 4-methylpentene and otherα-alkenes having at least 2 carbon atoms, and also for mixtures thereof.Copolymers of the above can produce desirable results such as broaderMWD and multi-modal distributions such as bimodal and trimodalproperties. The catalysts of the present invention can be utilized forthe polymerization of ethylene to produce polyethylene.

Various polymerization processes can be employed with the presentinvention, such as for example, single and/or multiple loop processes,batch processes or continous processes not involving a loop-typereactor. An example of a multiple loop process that can employ thepresent invention is a double loop system in which the first loopproduces a polymerization reaction in which the resulting polyolefin hasa lower MW than the polyolefin produced from the polymerization reactionof the second loop, thereby producing a resultant resin having broadmolecular weight distribution and/or bimodal characteristics. In thealternative, another example of a multiple loop process that can employthe present invention is a double loop system in which the first loopproduces a polymerization reaction in which the resulting polyolefin hasa greater MW than the polyolefin produced from the polymerizationreaction of the second loop, thereby producing a resultant resin havingbroad molecular weight distribution and/or bimodal characteristics.

The polymerization process may be, for example, bulk, slurry or gasphase. A catalyst of the invention can be used in slurry phasepolymerization. Polymerization conditions (e.g., temperature andpressure) are dependent upon the type of equipment utilized in thepolymerization process, as well as the type of polymerization processutilized, and are known in the art. Generally, the temperature will bein a range of about 50-110° C., and the pressure in a range of about10-800 psi.

The activity of the resulting catalyst of embodiments of the presentinvention is at least partially dependent upon the polymerizationprocess and conditions, such as, for example, equipment utilized andtemperature of reaction. For example in the embodiment of polymerizationof ethylene to produce polyethylene, generally the catalyst will have anactivity of at least 5,000 g PE/g catalyst but can have an activity ofgreater than 50,000 g PE/g catalyst, and the activity may be greaterthan 100,000 g PE/g catalyst.

Additionally, the resulting catalyst of the present invention canprovide a polymer with improved fluff morphology. Thus, the catalyst ofthe present invention can provide for large polymer particles with auniform distribution of sizes, wherein fine particles (less than about125 microns) are only present in low concentrations, such as forexample, less than 2% or less than 1%. The catalysts of the presentinvention, which include large, readily transferred powders with highpowder bulk densities, are amenable to polymerization productionprocesses. Generally the catalysts of the invention provide polymer withfewer fines and higher bulk densities (B.D.) wherein the B.D. value canbe greater than about 0.31 g/cc, can be greater than about 0.33 g/cc,and can even be greater than about 0.35 g/cc.

The olefin monomer may be introduced into the polymerization reactionzone in a diluent that is a nonreactive heat transfer agent that is aliquid at the reaction conditions. Examples of such a diluent are hexaneand isobutane. For the copolymerization of ethylene with anotheralpha-olefin, such as, for example, butene or hexene, the secondalpha-olefin may be present at 0.01-20 mole percent, and can be presentat between about 0.02-10 mole percent.

Optionally, an electron donor may be added with the halogenation agent,the first halogenation/titanation agent, or the subsequenthalogenation/titanation agent or agents. It may be desirable to have anelectron donor utilized in the second halogenation/titanation step.Electron donors for use in the preparation of polyolefin catalysts arewell known, and any suitable electron donor may be utilized in thepresent invention that will provide a suitable catalyst. Electrondonors, also known as Lewis bases, are organic compounds of oxygen,nitrogen, phosphorous, or sulfur which can donate an electron pair tothe catalyst.

The electron donor may be a monofunctional or polyfunctional compound,can be selected from among the aliphatic or aromatic carboxylic acidsand their alkyl esters, the aliphatic or cyclic ethers, ketones, vinylesters, acryl derivatives, particularly alkyl acrylates or methacrylatesand silanes. An example of a suitable electron donor is di-n-butylphthalate. A generic example of a suitable electron donor is analkylsilylalkoxide of the general formula RSi(OR′)₃, e.g.,methylsilyltriethoxide [MeSi(OEt₃)], where R and R′ are alkyls with 1-5carbon atoms and may be the same or different.

For the polymerization process, an internal electron donor can be usedin the synthesis of the catalyst and an external electron donor orstereoselectivity control agent (SCA) to activate the catalyst atpolymerization. An internal electron donor may be used in the formationreaction of the catalyst during the halogenation orhalogenation/titanation steps. Compounds suitable as internal electrondonors for preparing conventional supported Ziegler-Natta catalystcomponents include ethers, diethers, ketones, lactones, electron donorscompounds with N, P and/or S atoms and specific classes of esters.Particularly suitable are the esters of phthalic acid, such asdiisobutyl, dioctyl, diphenyl and benzylbutylphthalate; esters ofmalonic acid, such as diisobutyl and diethylmalonate; alkyl andarylpivalates; alkyl, cycloalkyl and arylmaleates; alkyl and arylcarbonates such as diisobutyl, ethyl-phenyl and diphenylcarbonate;succinic acid esters, such as mono and diethyl succinate.

External donors which may be utilized in the preparation of a catalystaccording to the present invention include organosilane compounds suchas alkoxysilanes of general formula SiR_(m)(OR′)_(4-m) where R isselected from the group consisting of an alkyl group, a cycloalkylgroup, an aryl group and a vinyl group; R′ is an alkyl group; and m is0-3, wherein R may be identical with R′; when m is 0, 1 or 2, the R′groups may be identical or different; and when m is 2 or 3, the R groupsmay be identical or different.

The external donor of the present invention can be selected from asilane compound of the following formula:

wherein R₁ and R₄ are both an alkyl or cycloalkyl group containing aprimary, secondary or tertiary carbon atom attached to the silicon, R₁and R₄ being the same or different; R₂ and R₃ are alkyl or aryl groups.R₁ may be methyl, isopropyl, cyclopentyl, cyclohexyl or t-butyl; R₂ andR₃ may be methyl, ethyl, propyl, or butyl groups and not necessarily thesame; and R₄ may also methyl, isopropyl, cyclopentyl, cyclohexyl ort-butyl. Specific external donors are cyclohexylmethydimethoxy silane(CMDS), diisopropyldimethoxysilane (DIDS) cyclohexylisopropyldimethoxysilane (CIDS), dicyclopentyldimethoxysilane (CPDS) ordi-t-butyl dimethoxysilane (DTDS).

Polyethylene produced using the above described catalyst can have an MWDof at least 5.0, and can be greater than about 6.0.

The polyolefins of the present invention are suitable for use in avariety of applications such as, for example, an extrusion process, toyield a wide range of products. These extrusion processes include, forexample, blown film extrusion, cast film extrusion, slit tape extrusion,blow molding, pipe extrusion, and foam sheet extrusion. These processesmay comprise mono-layer extrusion or multi-layer coextrusion.

End use applications that can be made utilizing the present inventioncan include, for example, films, fibers, pipe, textile material,articles of manufacture, diaper components, feminine hygiene products,automobile components and medical materials.

All references cited herein, including research articles, all U.S. andforeign patents and patent applications, are specifically and entirelyincorporated by reference.

EXAMPLES

The invention having been generally described, the following examplesare provided merely to illustrate certain embodiments of the invention,and to demonstrate the practice and advantages thereof. It is understoodthat the examples are given by way of illustration and are not intendedto limit the scope of the specification or the claims in any manner.

The synthetic scheme employed for this family of catalysts is as follows(all ratios are relative to BEM):(BEM+0.03 TEAl+0.6 DIAE)+2.09 2-Ethylhexanol→Mg(OR)₂Mg(OR)₂+ClTi(OPr)₃→Solution ASolution A+(2TiCl₄/Ti(OBu)₄)→Catalyst B (MgCl₂ based support)Catalyst B+X TiCl₄→Catalyst CCatalyst C+0.156 TEAl→Final Catalyst

The optimal formulation was regarded as X=0.5 to 2, with zero to twowashes prior to preactivation of catalyst C with TEAl. The followingmodifications were made to the catalyst preparation for a more effectivetitanation:Catalyst B+X TiCl₄→Catalyst CCatalyst C+Y TiCl₄→Catalyst DCatalyst D+0.156 TEAl→Final Catalyst

As shown, TiCl₄ addition is completed in two steps where X and Y=0.5 to1.0. Catalyst C is generally washed one to two times, while two washesare completed after Y to remove soluble titanium species that act assecond generation Ziegler species.

Example 1

In the nitrogen purge box, 1412.25 g (2.00 moles) of BEM-1, 27.60 g(0.060 moles) of TEAl (24.8% in heptane), and 189.70 g (1.20 moles) ofDIAE were added to a 3 L round bottom flask. The contents were thentransferred to the 20 L Buchi reactor via cannula under a nitrogen flow.The flask was then rinsed with approximately 400 ml of hexane which wastransferred to the reactor. The stirrer was set to 350 rpm.

The 2-ethylhexanol (543.60 g, 4.21 moles) was added to a 1 L bottle andcapped. It was then diluted to a total volume of 1 L with hexane priorto addition to the reactor. This solution was transferred to the reactorvia cannula using the mass flow controller. The initial head temperaturewas 25.3° C. and reached a maximum temperature of 29.6° C. Following theaddition (approximately 2 hours), the bottle was rinsed with 400 ml ofhexane which was transferred to the reactor. The reaction mixture wasleft stirring at 350 rpm overnight under a nitrogen pressure of 0.5 barand the heat exchanger was turned off.

The heat exchanger was turned on and set to 25° C. The chlorotitaniumtriisopropoxide was added to two 1 L bottles (774.99 and 775.01 g, 2.00total moles) to give a total of two liters. The contents of each bottlewere transferred to the reactor via cannula using the mass flowcontroller. The initial head space temperature was 24.6° C. and reacheda maximum temperature of 25.9° C. during the addition of the secondbottle. The addition times were 145 and 125 minutes for bottles 1 and 2,respectively. After the addition, each bottle was rinsed with 200 ml ofhexane which was transferred to the reactor. The reaction mixture wasleft stirring at 350 rpm overnight under nitrogen pressure of 0.5 bar.The heat exchanger was turned off.

Preparation of TiCl₄/Ti(OBu)₄ The titanium tetrachloride/titaniumtetrabutoxide mixtures were prepared in a 5 liter round bottom flaskusing standard schlenk line techniques. In a 1 L pressure bottle, 680.00g (1.99 moles) of Ti(OBu)4 was diluted to 1 L total volume with hexane.This solution was then cannula transferred to the reactor. The bottlewas rinsed with 200 ml of hexane and transferred to the reactor. In a 1L measuring cylinder, 440 ml (˜760 g, 4.00 moles) of TiCl₄ was dilutedto a total volume of 1 L with hexane. The solution in the 5 liter flaskwas stirred and the TiCl₄ solution was added to the reactor dropwiseunder N₂ pressure via cannula. After the addition was complete, the 1 Lcylinder was rinsed with 200 ml of hexane which was transferred to thereactor. After 1 hour, the reaction mixture was diluted to 4 L totalvolume with hexane and stored in the flask prior to use.

The heat exchanger was turned on and set to 25° C. The TiCl₄/Ti(OBu)₄mixture was transferred to the 20 liter reactor via cannual and massflow controller. The initial head space temperature was 24.7° C. andreached a maximum temperature of 26.0° C. during the 225 minuteaddition. Following the additions, the vessel was rinsed with one literof hexane and allowed to stir for 1 hour.

The stirrer was turned off and the solution allowed to settle for 30minutes. The solution was decanted by pressuring the reactor to 1 bar,lowering the dip tube, and making sure no solid catalyst came throughthe attached clear plastic hose. The catalyst was then washed threetimes using the following procedure. Using a pressure vessel on abalance, 2.7 kg of hexane was weighed into the vessel and thentransferred to the reactor. The stirrer was turned on and the catalystmixture was agitated for 15 minutes. The stirrer was then turned off andthe mixture was allowed to settle for 30 minutes. This procedure wasrepeated. After the third addition of hexane, the slurry was allowed tosettle overnight and the heat exchanger was turned off.

The supernatant was decanted, and 2.0 kg of hexane added to the reactor.Stirring was resumed at 350 rpm and the heat exchanger was turned on andset to 25° C. In a one liter graduated cylinder, 440 milliliters (760 g,4.00 moles) of titanium tetrachloride were added. The TiCl₄ was dilutedto one liter with hexane, and half of the solution was transferred tothe reactor via cannula and mass flow controller. The initial headtemperature of 24.7° C. increased 0.5° C. during the addition. The totaladdition time was 45 minutes. After one hour, the stirrer was turned offand the solids were allowed to settle for 30 minutes. The supernatantwas decanted, and the catalyst was washed once with hexane following theprocedures described above. After the wash was complete, 2.0 kg ofhexane was transferred to the reactor and the agitation was resumed. Thesecond TiCl₄ drop was completed in a similar manner to that describedabove using the remaining 500 milliliters of solution. Following theaddition, the cylinder was rinsed with 400 milliliters of hexane, whichwas added to the Buchi. After one hour of reaction, the stirrer wasturned off and the solids were allowed to settle for 30 minutes. Thesupernatant was then decanted, and the catalyst washed three times withhexane. 2.0 kg of hexane was then transferred to the reactor.

In a one liter pressure bottle, 144.8 g (312 mmol) of TEAl (25.2% inhexane) were added. The bottle was capped and diluted to one liter withhexane. This solution was then transferred to the reaction mixture viacannula using the mass flow controller. During the 120 minute addition,the color of the slurry turned dark brown. The initial head temperaturewas 24.5° C. and reached a maximum temperature of 25.3° C. Following theaddition, the bottle was rinsed with 400 milliliters of hexane, whichwas transferred to the reactor. After 1 hour of reaction, the stirrerwas shut off and the catalyst was allowed to settle for 30 minutes. Thesupernatant was decanted and the catalyst was washed once following theprocedures previously described. Following the wash, 2.7 kg of hexanewas added to the reactor. The contents were then transferred to a threegallon pressure vessel. The Buchi was rinsed with 1.0 kg and 0.5 kg ofhexane, which were added to the pressure vessel. Estimated catalystyield was 322 g.

In one embodiment the composition in weight percent was: Cl 53.4%; Al2.3%; Mg 11.8% and Ti at 7.9%. Observed ranges for each element were; Clat 48.6-55.1%; Al at 2.3-2.5%; Mg at 11.8-14.1%; and Ti of 6.9-8.7%.Ranges for each element can be; Cl at 40.0-65.0%; Al at 0.0-6.0%; Mg at6.0-15.0%; and Ti of 2.0-14.0%.

Table 1 lists the [Ti] measured from samples after the TiCl4/Ti(OBu)₄addition, three washes, a first TiCl₄ addition, one wash and the secondTiCl₄ addition and three subsequent washes. Decants 1-4 are followingthe TiCl4/Ti(OBu)₄ addition. Decants 5 and 6 are following the firstTiCl₄ addition. Decants 7-10 follow the second TiCl₄ addition.

TABLE 1 Decant Sample Ti (ppm) mmol/L 1 2.1 21000 306.9 2 0.8 8000 116.93 0.2 2000 29.2 4 0.1 1000 14.6 5 2 20000 292.3 6 0.4 4000 58.5 7 1.919000 277.7 8 0.4 4000 58.5 9 0.0925 925 13.5 10 0.0064 64 0.9

Comparative Example 1:

Comparative Example 1 was prepared in a similar manner to that ofExample 1 except the third titanation was omitted and the secondtitantion was carried out employing one fourth of the quantity of TiCl₄

Comparative Example 2:

Comparative Example 2 was prepared in a similar fashion to Example 1except a second and third titantion step was performed employing 0.5equivalents of TiCl₄ during each titanation step.

Comparative Example 3

Comparative Example 3 was prepared in a similar manner to ComparativeExample 1 except the quantity of TiCl₄ employed during the secondtitanation was approximately four times that used during ComparativeExample 1. One hexane wash was performed following the secondtitanation. In one embodiment the composition in weight percent was: Clat 57.0%; Al at 2.0%; Mg at 9.5% and Ti at 10.0%. Ranges for eachelement can be; Cl at 55.0-57.0%; Al at 2.0-2.6%; Mg at 8.9-9.5%; and Tiof 10.0-11.0%.

Comparative Example 4

Comparative Example 4 was prepared in a similar manner to ComparativeExample 3 except two hexane washes were performed following the secondtitanation. In one embodiment the composition in weight percent was: Cl53.0%; Al 2.3%; Mg 9.7% and Ti at 9.5%. Ranges for each element can be;Cl at 52.6-53.0%; Al at 2.0-2.3%; Mg at 9.7-10.6%; and Ti of 8.7-9.5%.

Table 2 lists the catalysts prepared.

TABLE 2 Number of Number of Catalyst X washes Y washes ComparativeExample 1 0.5 0 0 NA Comparative Example 2 0.5 1 0.5 2 Example 1 1.0 11.0 2 Comparative Example 3 2.0 1 0 NA Comparative Example 4 2.0 2 0 NA

Table 3 gives the MWD data provided for polymers made with Example 1 andComparative Examples 1 to 4. For a given catalyst/cocatalyst system, thedata show that a narrower MWD can be attained by increasing the numbersof washes or addition of a third titanation step with TiCl₄. In general,the polymer resin intrinsic MWD increases in the following orderComparative Example 1<Comparative Example 2<Comparative Example4<Example 1<Comparative Example 3.

TABLE 3 Number of Number of Washes Washes Co- following following SR5 DCatalyst catalyst X Y (HLMI/MI₅) (Mw/Mn) Comparative TEA1 0 0 10.9 6.2Example 1 Comparative TEA1 1 2 10.9 NA Example 2 Example 1 TEA1 1 2 12.66.8 Comparative TEA1 1 NA 11.8-12.8 5.9-6.8 Example 3 Comparative TEA1 2NA 10.8-12.0 6.0-6.3 Example 4 Example 1 TIBA1 1 2 11.9 7.0 ComparativeTIBA1 1 NA 12.2-13.6 6.9-7.3 Example 3 Comparative TIBA1 2 NA 11.4-11.86.6-7.5 Example 4

As shown in Table 4, each of the catalysts provides powder with lowlevels of fines (particles less than 125 microns); however, catalysts ofthe invention prepared with two titanation steps consistently providefluff with higher bulk densities.

TABLE 4 D₅₀ Fluff D₅₀ B.D. Catalyst (microns) (microns) % Fines (g/cc)Comparative Example 1 9.4 260 0.0 0.38 Comparative Example 2 7.8 237 0.60.40 Comparative Example 4 10.1 287 1.6 0.34 Example 1 9.2 264 0.6 0.38

These properties have substantial effects on the settling efficiency ofthe polymer as demonstrated by the laboratory derived settlingefficiency curves provided in FIG. 1. The rapid disappearance of theinitial 10 ml of fluff from solution exhibited by the inventive polymermade with the inventive catalyst of Example 1 implies a greater settlingrate and better polymer morphology than that made with conventionalcatalyst of comparative Example 4.

While the illustrative embodiments of the invention have been describedwith particularity, it is understood that various other modificationscan be readily made by those skilled in the art without departing fromthe scope of the invention.

1. A process for making a catalyst component comprising: a) generating areaction product A by contacting a magnesium dialkoxide compound with ahalogenating agent; b) contacting reaction product A with a firsthalogenating/titanating agent to form reaction product B; c) contactingreaction product B with a second halogenating/titanating agent to formreaction product C; and d) contacting reaction product C with a thirdhalogenating/titanating agent to form catalyst component D.
 2. Theprocess of claim 1 wherein the halogenating agent is of the generalformula ClAR′″_(x), wherein A is a nonreducing oxyphilic compound, R′″is a hydrocarbyl moiety having from about 2 to 6 carbon atoms, and x isthe valence of A minus
 1. 3. The process of claim 1 wherein thehalogenating agent is ClTi(O^(i)Pr)₃.
 4. The process of claim 1 whereinthe first halogentating/titanating agent is a blend of twotetra-substituted titanium compounds with all four substituents beingthe same and the substituents being a halide or an alkoxide or phenoxidewith 2 to 10 carbon atoms.
 5. The process of claim 4 wherein the firsthalogentating/titanating agent is a blend of a titanium halide and anorganic titanate.
 6. The process of claim 5 wherein the firsthalogentating/titanating agent is a blend of TiCl₄ and Ti(OBu)₄ in arange from 0.5:1 to 6:1 TiCl₄/Ti(OBu)₄.
 7. The process of claim 1wherein the second and third halogenating/titanating agents comprisetitanium tetrachloride.
 8. The process of claim 7 wherein steps c) andd) each comprise a titanium tetrachloride to magnesium ratio in therange of about 0.1 to about
 5. 9. The process of claim 1 whereinreaction products A, B, and C are washed with a hydrocarbon solventprior to subsequent halogenating/titanating steps.
 10. The process ofclaim 9 wherein reaction products A, B, and C are washed with ahydrocarbon solvent until titanium species [Ti] content is less thanabout 100 mmol/L prior to subsequent halogenating/titanating steps. 11.The process of claim 1 wherein the reaction product D is washed with ahydrocarbon solvent until titanium species [Ti] content is less thanabout 20 mmol/L.
 12. The process of claim 1 wherein an electron donor ispresent in any one or more of steps a), b), c), or d), and wherein theratio of electron donor to metal is in the range of about 0:1 to about10:1.
 13. The process of claim 1 further comprising placing the catalystof the invention on an inert support.
 14. The process of claim 13wherein the inert support is a magnesium compound.
 15. The process ofclaim 1 further comprising: e) contacting D with an organometallicpreactivating agent to form a preactivated catalyst system.